1. Field of the Invention
The invention relates generally to methods for manufacturing light guide plates and, more particularly, to a method for manufacturing a light guide plate used in liquid crystal display devices.
2. Discussion of Related Art
Liquid crystal display devices have many excellent performance characteristics, such as large-scale information display ability, easy to color, low power consumption, long life, no pollution associated therewith, and so on. Therefore, liquid crystal display devices are used widely in such devices as mobile telephones, personal digital assistants (PDA), personal media players (PMP), portable DVD, notebooks, and display devices used in autos. The liquid crystal display devices, however, are passive and can't luminesce. Thus, a typical liquid crystal display device usually adopts a backlight module as its light source. The backlight module generally includes a light guide plate and a light source.
The light source can be located beside one end or beside two opposite ends of the light guide plate and is used to emit incident light beams into the light guide plate. The light guide plate is used to lead travel (i.e., direct) of the incident light beams therein and ensure that most of the incident light beams can be emitted from an emission surface thereof. Thus, by employing such a light guide plate, linear light sources, such as cold cathode ray tubes, or point light sources, such as light emitting diodes, can be converted into area light sources.
In order to enhance a uniformity of the emitted light beams, a plurality of dots can be formed on the emission surface of the light guide plate. The dots are able to break up what could otherwise be a total reflection condition of the incident light beams. This light diffusion ensures that most of the incident light beams can pass through the light emitting surface of the light guide plate.
The light guide plate is generally manufactured by means of injection molding. The injection molding method generally includes the following steps: feedstock is fed in a heated container of an injection molding device and is melted; the molten feedstock is then injected into a mold of the injection molding device; and the molten material is cooled and solidified in the mold to form the light guide plate.
The dots on the light guide plate manufactured by means of injection molding can enhance, to a certain extent, the uniformity of the emitted light beams from the light guide plate. However, a size of each dot is about several tens of micrometers (i.e., from 10 micrometers to 99 micrometers) and is thus not fine (i.e., with respect to the surface microstructure). That is to say, given the limitations on currently-available injection molds, it is difficult to achieve entire or even substantial uniformity of the emitted light beams from the whole area of the light guide plate.
What is needed, therefore, is a method which can manufacture a light guide plate having an array of fine (i.e., with respect to microstructure) dots.